[BUG] data-order not working with negative numbers

[Stoakes]

• I have looked through the documentation to try to see if this behavior is documented.
• I have looked at the demos to see if one of them handles this, but none of them did.

Describe the bug
Hello, thanks a lot for this library !

I think I found a bug : when setting the data-order attribute on cells and using negative values, the ordering doesn't work as expected.

To Reproduce

I have created this jsfiddle to demonstrate the issue : https://jsfiddle.net/6Lpjnqrk/

Steps to reproduce the behavior:

1. Go to https://jsfiddle.net/6Lpjnqrk/
2. Click on Variation header to sort the column (asc or desc, doesn't matter)
3. The rows are not ordered according to data-order value. Negative values are not taken into account. Even if it was sorted based on string value, that wouldn't look like that.

Name	Variation (ordered by asc)
MSFT	0.0%
FB	0.4%
AAPL	-0.5%
PG	-0.41%
NVIDIA	1.6%

Expected behavior
Values should be ordered according to data-order value :

Name	Variation (asc)
AAPL	-0.5%
PG	-0.41%
MSFT	0.0%
FB	0.4%
NVIDIA	1.6%

Additional context
This doesn't seem to be an issue related to floats. It behaves the same when using integers in data-order.

Have a good day

[Stoakes]

Thanks for taking care of this one so fast.

I confirm it's now working as intended with negative numbers.